and shorter target substems were adopted in 2009. They mostly consist of a consonant, plus a vowel which is omitted if the source substem begins with a vowel. For example, human antibodies targeting the immune system receive names ending in -lumab instead of the old -limumab. Some endings like -ciximab remained unchanged. The old system employed seven different substems for tumor targets, depending on the type of tumor. Because many antibodies are investigated for several tumor types, the new convention only has -t(u)-. With the source substem being discontinued in 2017, the need for dropping the target substem's final vowel disappeared. Prefix The prefix carries no special meaning. It should be unique for each medicine and contribute to a well-sounding name. This means that antibodies with the same source and target substems are only distinguished by their prefix. Even antibodies targeting exactly the same structure are differently prefixed, such as the adalimumab and golimumab, both of which are TNF inhibitors but differ in their chemical structure. Additional words A second word following the name of the antibody indicates that another substance is attached, which is done for several reasons. An antibody can be PEGylated (attached to molecules of polyethylene glycol) to slow down its degradation by enzymes and to decrease its immunogenicity; this is shown by the word pegol as in alacizumab pegol. A cytotoxic agent can be linked to an anti-tumor antibody for drug targeting purposes. The word vedotin, for example, stands for monomethyl auristatin E which is toxic by itself but predominantly affects cancer cells if used in conjugates like glembatumumab vedotin. A chelator for binding a radioisotope can be attached. Pendetide, a derivative of pentetic acid, is used for example in capromab pendetide to chelate indium-111. If the drug contains a radioisotope, the name of the isotope precedes the name of the antibody. Consequently, indium (111In) capromab pendetide is the name for the above example including indium-111. Overview History Emil von Behring and Kitasato Shibasaburō discovered in 1890 that diphtheria and tetanus toxins were neutralized in the bloodstream of animals by substances they called antitoxins, which were specific for the respective toxin. Behring received the first Nobel Prize in Physiology or Medicine for their find in 1901. A year after the discovery, Paul Ehrlich used the term antibodies (German Antikörper) for these antitoxins. The principle of monoclonal antibody production, called hybridoma technology, was published in 1975 by